A determinação do magnésio trocável do solo pelo método espectrofotométrico do metiltimol azul

Abstract

This paper describes a study on the determination of magnesium in soils by the spectrophotometric method of methylthymol blue. Data about the absorption spectra and the stability of the compound are related. In the study of the interferents several ions were considered. Calcium yields with the reagent a colored compound which absorbs in the same wavelenght as magnesium, and is eliminated by precipitation with ammonium oxalate solution. The magnesium of the soil is extracted by KC1 1 N solution.